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Soldering 101

The ability to solder is an extremely useful skill in the field of electronics. Entry-level electronic assemblers can make 2-3 times minimum wage if they have proficiency with this. If you follow the fundamentals it is not very difficult to do standard through-hole components. Basically, solder is an alloy that melts at low temperature and is used to join 2 other metals (such as a component lead to a circuit board plated-through hole or a wire to a post). When I was 10, I used a gas stove and a rusty nail held by a pair of pliers to solder my first working circuit; though there is no real substitute for a quality soldering iron or soldering station. One distinction between an iron and a station is that a station should have a way of holding the iron safely so it does not burn you nor your work surface. My standard soldering temperature is 700 degrees Fahrenheit (371 C).

Wash your hands after soldering. No food or drinks near the soldering area.

Soldering Technique

Proper soldering technique is when your tip is clean with a shiny thin coating of solder at 700 F. You are to evenly heat both the part and the pad (or both parts) then feed the joint solder wire as it melts. You pull the solder and its spool away from the joint, then the soldering tip so the joint can cool. You should be left with a nice meniscus of solder with a concave surface.

Tip Cleaning

Pictured above is brass wool. You simple shove a heated soldering tip in and out to remove oxides and slag. An alternative is to use a regular kitchen sponge that is slightly damp.

Solder Removal

If your first soldering efforts end up as an ugly blob; do not despair; one remedy is to use solder wick to remove the solder through capillary action. You simply place the desoldering braid over the solder and heat both until the offending solder ‘wicks away’.

Another popular method is using a solder-sucker which has a spring-loaded plunger to create a little vacuum force to pull the solder into the tube.

Last and least is the old-school desoldering bulb; which reminds me of how I had to chase my runny-nosed children around the house when they were toddlers.

Our solder is a tin/lead alloy. You need to wash your hands with soap and water after soldering. Also, the tip is hot enough to give you a 3rd degree burn instantly; be very careful how you handle your soldering iron. Keep the iron in its holder when not in use; and never leave an unattended soldering iron on. Use safety glasses or goggles while soldering.

In this exercise you will solder the header pins to your Arduino Nano board.

The trick so your rows of header pins do not come out crooked is to use your breadboard to hold them in place so they will be at a right-angle to the Arduino PCB (printed circuit board).

Solder your first pin and permit one of the Makerspace helpers to look at it and offer some guidance if necessary. Or have them solder a few pins while you watch and then finish the rest. Your Arduino Nano will remain in this position for the duration of the course.

Soldering Speaker Wires

You will need to sacrifice 2 jumper wires for your 8 ohm speaker (they need not be any particular color for our purposes). You will need to cut off one end of the jumper and strip off the insulation. Twist the loose wires together with your finger tips and pre-tin the stripped wires before soldering them to the speaker terminals. I would recommend following up with some hot-melt glue to secure the wires as a strain relief.

Soldering Piezo Element

We also need to attach wires to the piezo element; this time we do care about the polarity; so let us follow the picture above for the red and black wires. The piezo can be damaged if too much heat is applied; the technique is to put a drop of solder on the rim and another on the closest white edge and pre-tin the wires and finally quickly reflow the wires to the piezo element.

Published by jamesmdinsmore

Engineering Specialist; over 30 years of technical experience; on the board of directors at MelbourneMakerSpace.org (Florida, USA) Deeply committed to open source and knowledge sharing. Love Linux, Arduino, Raspberry Pi and blogging.
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